I was going thru some cars on the game today, and after a friend bought one of the FE i had, i was going to look for a Chevy Impala lowrider to buy, when i saw that there’s noone., nor any normal non-lowrider '64 Impala.
Anyone else who got the same issue not having some cars that’s not DLC cars suddenly in the game?
Some cars are not available straight from the shop, like the '14 BMW M4, or the 2005 Ford GT. They can be acquired through Forzathon, specialty dealer or as special rewards for certain races/events. Or maybe check the auction house 
The forza edition i understand, but the normal Chevy Impala from 1964 for me is gone like it’s not a car you can buy. Is that not strange?
No, it is a ‘locked’ car that you can buy in the Specialty Dealer:
https://forums.forzamotorsport.net/turn10_postst99201_FM7-Car-List-and-How-to-Get-Locked-Cars.aspx?=
it’s in this weeks specialty dealer
it’s also the second time round for this to be available there
I not sure about the impala, but some cars are won through the career mode. It might acquired through there.